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Lodi Vecchio, Italy

da Silva Linge C.,University of Milan | Bassi D.,University of Milan | Bianco L.,Research and Innovation Center | Pacheco I.,University of Milan | And 3 more authors.
Molecular Breeding | Year: 2015

Fruit weight is a quantitative trait influenced by the combined action of several genes and environmental factors. Knowledge of the quantitative trait loci (QTLs) associated with fruit weight and size is a priority to support breeding programmes in peach (Prunus persica (L.) Batsch) because of commercial interest in larger fruits. To this end, we built a genetic map of an F2 progeny of 117 individuals from the cross PI91459 (‘NJ Weeping’) × ‘Bounty’ using a single nucleotide polymorphism (SNP) genotyping array for peach (9K SNP array v1). Data for fruit weight, height, width, and depth were recorded for the progeny and both parents over 2 years (2011, 2012). Correlations between the traits fruit weight and size were positive and significant for both years. A SNP map was constructed comprising 1,148 markers distributed over eight linkage groups. The map spans 536.6 cM with an average distance between markers of 0.52 cM, covering 93.6 % of the physical length of the peach genome, thus representing an ideal basis for QTL mapping. QTL analysis led to the identification of a total of 28 QTLs for the considered traits, eleven of which remained stable in both years. We also observed clusters of QTLs, some of which were mapped for the first time, while others correspond to loci previously identified in different progenies and following different approaches. © 2015, Springer Science+Business Media Dordrecht. Source

Pirona R.,Plant Genomics Section | Vecchietti A.,Plant Genomics Section | Lazzari B.,Bioinformatics Section | Caprera A.,Bioinformatics Section | And 8 more authors.
Plant Biology | Year: 2013

The expression profile of flavour-related genes during ripening was investigated in two peach genotypes, Bolero and OroA, which have been selected for their contrasting aroma/ripening behaviour. A new peach microarray containing 4776 oligonucleotide probes corresponding to a set of ESTs specifically enriched in secondary metabolism (μPEACH2.0) was designed to investigate transcriptome changes during three fruit ripening stages, revealing 1807 transcripts differentially expressed within and between the two genotypes. Differences in the expression of genes involved in the biosynthesis of aroma compounds were detected during the ripening process within and between the two genotypes. In particular, a subset of 12 transcripts involved in metabolism of esters, norisoprenoids, phenylpropanoids and lactones, varied in expression during ripening and between Bolero and OroA. © Parco Technologico Padona S.r.l. © 2012 German Botanical Society and The Royal Botanical Society of the Netherlands. Source

Pirona R.,Plant Genomics Section | Eduardo I.,Plant Genomics Section | Pacheco I.,University of Milan | Da Silva Linge C.,University of Milan | And 9 more authors.
BMC Plant Biology | Year: 2013

Background: Maturity date (MD) is a crucial factor for marketing of fresh fruit, especially those with limited shelf-life such as peach (Prunus persica L. Batsch): selection of several cultivars with differing MD would be advantageous to cover and extend the marketing season. Aims of this work were the fine mapping and identification of candidate genes for the major maturity date locus previously identified on peach linkage group 4. To improve genetic resolution of the target locus two F2 populations derived from the crosses Contender x Ambra (CxA, 306 individuals) and PI91459 (NJ Weeping) x Bounty (WxBy, 103 individuals) were genotyped with the Sequenom and 9K Illumina Peach Chip SNP platforms, respectively. Results: Recombinant individuals from the WxBy F2 population allowed the localisation of maturity date locus to a 220 kb region of the peach genome. Among the 25 annotated genes within this interval, functional classification identified ppa007577m and ppa008301m as the most likely candidates, both encoding transcription factors of the NAC (NAM/ATAF1, 2/CUC2) family. Re-sequencing of the four parents and comparison with the reference genome sequence uncovered a deletion of 232 bp in the upstream region of ppa007577m that is homozygous in NJ Weeping and heterozygous in Ambra, Bounty and the WxBy F1 parent. However, this variation did not segregate in the CxA F2 population being the CxA F1 parent homozygous for the reference allele. The second gene was thus examined as a candidate for maturity date. Re-sequencing of ppa008301m, showed an in-frame insertion of 9 bp in the last exon that co-segregated with the maturity date locus in both CxA and WxBy F2 populations. Conclusions: Using two different segregating populations, the map position of the maturity date locus was refined from 3.56 Mb to 220 kb. A sequence variant in the NAC gene ppa008301m was shown to co-segregate with the maturity date locus, suggesting this gene as a candidate controlling ripening time in peach. If confirmed on other genetic materials, this variant may be used for marker-assisted breeding of new cultivars with differing maturity date. © 2013 Pirona et al.; licensee BioMed Central Ltd. Source

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